You win some, you lose some

THE jack of all trades really is a master of none, at least when it comes to sport. In a study of world-class decathletes, biologists have confirmed that a flair for certain sporting events undermines your abilities in other competitions.

Biologists have long argued that physiological trade-offs affect animals' physical abilities. For instance, speedy animals rely on fast, very elastic muscle, but endurance depends on slower fibres that are more resistant to fatigue. "The cheetah is the fastest land animal, but it also has a very poor ability to sustain locomotion over long distances," points out Robbie Wilson of the University of Antwerp in Belgium.

Evidence for these trade-offs has been largely anecdotal, however. To find out if they also affect people, Wilson and his team analysed scores for 600 decathletes, who compete in 10 gruelling events over two days.